The present invention relates to a safety indwelling needle comprised of a soft outer needle to be inserted and placed within a blood vessel and a hard inner needle which is fitted in the outer needle and pierces the skin of a patient to introduce the outer needle into a blood vessel.
As a known method for infusing a medical fluid or the like into a patient, an outer needle (catheter) is inserted and placed in the human body to infuse the fluid through this outer needle. As a device for guiding the outer needle, indwelling needles have been known to insert and place the outer needle using the inner needle fitted in the outer needle.
The inner needle is discarded after placement of the outer needle in the human body, but it takes a certain time before the inner needle is discarded. Therefore, if an indwelling needle has no safety mechanism there is a risk of pricking the fingers etc. of health care workers by the inner needle during this period or a so-called needlestick accident occurring. If the patient is infected with the HIV virus or the like, there is a risk that the health care worker might catch the virus or the like from a needlestick accident.
In order to solve this problem, many types of safety indwelling needles which avoid needlestick injuries by covering the inner needle immediately after use have been developed. For example, Japanese Patent Application Laid-Open Hei 3 No.15481 offers a cannula inserting device for retracting a needle hub, which might cause a needlestick, into a hollow handle by means of an urging means.
Alternatively, Japanese Patent Application Laid-Open No.2000-167051, Japanese Patent Application Laid-Open No.2000-185096 etc. present technologies relating to a safety indwelling needle (puncture device) having a retracting mechanism for retracting the inner needle immediately after use into the holder sleeve. These technologies present techniques whereby the inner needle is retracted by means of an urging means when an actuating element is operated in a peripheral direction of the holder sleeve so that the actuating element is fixed to a cutout formed in the holder sleeve.
However, since the device disclosed in Japanese Patent Application Laid-Open 3 No.15481 is constructed so that the mechanism will be released by pressing an element corresponding to a trigger inwardly from the outside of the holder cylinder, this configuration frequently causes wrong actuation such that the trigger is pressed erroneously and the inner needle is retracted when it shouldn""t.
On the other hand, the safety indwelling needles disclosed in Japanese Patent Application Laid-Open No.2000-167051, Japanese Patent Application Laid-Open No.2000-185096 etc., are free from the problem of the wrong actuation due to unintended pressing, but these configurations need an actuation in the peripheral direction of the holder sleeve after retraction of the inner needle. Therefore, there is the problem with the devices which causes difficulties in handling, depending on the left or right handedness. In order to solve this problem, two types of products for left and right handedness need to be prepared, which increases in the cost of manufacture and management, and also forces the users to select one from these two types.
The present invention has been devised under the above circumstances, it is therefore an object of the present invention to provide a technology for a safety indwelling needle which is almost never erroneously actuated and free from the problem of the actuation depending on the handedness.
In order to attain the above object, the present application provides the invention having the following configurations.
The present invention is directed to a safety indwelling needle, comprised of a soft outer needle to be inserted and placed within a blood vessel, a hard inner needle, with an inner needle hub, which is fitted in the outer needle, pierces the skin of a patient to introduce the outer needle into the blood vessel and a holder sleeve having an open distal end and a closed proximal end and capable of holding the inner needle, characterized in that: the holder sleeve incorporates an urging means f or urging the inner needle toward the proximal end side and an actuator which engages the inner needle at a near distal end portion of the holder sleeve so that the inner needle can be released and a tip of the inner needle is projected from the holder sleeve; the actuator has an inner needle hub fixed at a front end thereof and is formed with an actuating member projected outside the holder sleeve; the holder sleeve has a slit which extends to the proximal end side of the sleeve so as to hold and allow the actuating member of the actuator to slide and assures the path of movement of the actuator released from the near distal end portion of the holder sleeve; and the inner needle is adapted to be released from the holder sleeve when the actuating member is moved away from the holder sleeve within a same plane that includes the axis of the holder sleeve.
The inner needle (12) is a hard needle provided with an inner needle hub (12a) at the proximal end thereof. It is usually a metal, mostly made of stainless steel. The tip of the inner needle (12) is beveled in order to facilitate puncture.
The outer needle (11) is placed into the human body after puncture and usually formed of a flexible resin.
The holder sleeve (1) is usually formed of a translucent resin or the like. When the inner needle (12) is punctured into the human body, the blood passes through the inner needle (12) and reaches the inner needle hub (12a). Formation of these portions with a translucent material allows for confirmation of the blood reaching the inner needle hub (12a), hence makes possible visual recognition that the inner needle (12) has reached a blood vessel.
The inner diameter of the holder sleeve (1) is set greater than the inner needle hub (12a) and set smaller than the proximal part of the outer needle (11) or the outer needle hub (11a), so that the inner needle (12) can be retracted thereinto but the outer needle (11) will not be retracted.
The holder sleeve (1) incorporates an actuator (6) which engages an inner needle (12) at the near distal end portion of the holder sleeve (1) so that the inner needle (12) can be released and the tip of the inner needle is projected from the holder sleeve (1). An inner needle hub (12a) is fixed to this actuator (6). An actuating member (6a) is formed so as to project outside the holder sleeve (6). The holder sleeve (1) has a slit (2) which extends toward the proximal end side so as to hold and allow this actuating member (6a) to slide and assures the path of movement of the actuator (6) released from the near distal end portion of the holder sleeve (1).
As the urging means, string-like rubber (not shown), etc., may be employed other than a coil spring (8) which contracts when no load is applied.
The movement path of actuation is adapted to be included in the same plane that includes the axis of the holder sleeve (1). Hence, the problem due to the handedness can be eliminated, differing the case where the actuation is made by the rotational movement about the axis of holder sleeve
In the position in which the inner needle (12) is fixed by the actuator (6) at the near distal end portion of the holder sleeve (1) so that the inner needle (12) can be released and the needle tip is projected from the holder sleeve (1), the inner needle (12) and outer needle (11) are punctured into the skin of a patient. When the inner needle (12) and outer needle (11) have reached a blood vessel, the flow of blood through the blood vessel is stopped by hand while the holder sleeve (1) on another hand is pulled away from the patient so as to withdraw the inner needle (12) from the blood vessel. Then the actuating member (6a) of actuator (6) is operated so as to release the actuator (6) from the near distal end portion of the holder sleeve (1). In response to this, the inner needle (12) is urged toward the proximal end side of holder sleeve (1) by the urging means (8), so that the inner needle (12) moves, which is followed by the actuator (6) moving along the slit(2). On the contrary, the outer needle (11) will not retract into the holder sleeve (1) but remains at the set position, so as to be connected to an infusion tube, etc.
The inner needle (12) to move toward the proximal end side of the holder sleeve (1) is moved and held until its tip is completely withdrawn into holder sleeve (1). Since the retracted inner needle (12) is pulled by the coil spring (8) which contracts when no load is applied, the inner needle (12) will not be exposed outside, whereby it is possible to prevent occurrence of needlestick injuries.
In the present invention, for releasing the engagement by shifting the actuating member (6a) away from the holder sleeve, a structure for directly lifting the actuating member (6a) from the holder sleeve (1) is adopted. When the actuating member (6a) is moved away from the holder sleeve (1), the engagement between the holder sleeve (1) and inner needle (12) is released, whereby the inner needle (12) is withdrawn into the holder sleeve (1) by virtue of the coil spring (8). This action, differing from a depressing action, almost never causes an erroneous actuation.
Further, it is preferred that the actuating member has an engagement projection which can be fitted into an engagement window formed in the near distal end portion of the holder sleeve, and the actuator is fixed at the near distal end portion of the holder sleeve when the engagement projection is fitted in the engagement window, and the engagement between the actuator and holder sleeve is released when the engagement projection is pulled up from the engagement window.
According to this configuration, the actuating member (6a) of the actuator (6) is formed with an engagement projection (6b) while an engagement window (3) is formed at the front part of the holder sleeve (1). When this engagement projection (6b) is fitted into the engagement window (3), the actuator (6) is engaged with the holder sleeve (1), and the engagement between the actuator (6) and holder sleeve (1) is released when the engagement projection (6b) is pulled up from the engagement window (3). Therefore, the engaged state can be released by moving the actuating member (6a) of the actuator (6) away from the holder sleeve (1), hence this action, differing from a depressing action, almost never causes an erroneous actuation. When the engaged state between the holder sleeve (1) and actuating member (6a) is released, the inner needle (12) fixed to actuator (6) is retracted into the holder sleeve (1) by virtue of the coil spring (8).
It is also preferred that the actuating member is formed to be flexible and is joined to the actuator by a joint rod which is located closer to the proximal end side than the engagement projection is.
In the present invention, since the actuating member (6a) is formed to be flexible and is joined to the actuator (6) by joint rod (6c) which is located closer to the proximal end side than the engagement projection is, this facilitates smooth actuation. Illustratively, when the outer needle (11) is placed into the human body, the outer needle (11) is slightly pushed out by the second digit of the right hand, for example, so as to separate the outer needle (11) from the inner needle (12). At this moment, the second digit is located around an aftermentioned cutout portion (1f) of the holder sleeve (1). Therefore, the second digit is present slightly forwards with respect to the actuating member (6a). This allows the second digit to raise the actuating member (6a) immediately when the inner needle (12) needs to be retracted.
It is also preferred that a lift abutment (6d) on which the finger is abutted when the engagement projection (6b) is pulled up from the engagement window (3) is provided at the distal end portion of the actuating member (6a).
If no lift abutment (6d) for raising the actuating member (6a) is formed, this obstructs quick retraction of the inner needle (12). This is why a lift abutment (6d) is provided at the front part of the actuating member (6a) in the present invention, whereby a quicker and more reliable retraction of the inner needle (12) can be made.
It is preferred that the lift abutment (6d) is formed on the surface facing to the front as is shown in FIG. 4. It is also preferred that the angle a between the axis and the lift abutment (6d) is set at 90 degrees or smaller because this makes it possible for the lift abutment (6d) to hook the finger reliably.
Moreover, it is preferred that anti-slip such as serration is formed because this also enables quick reliable retraction of the inner needle (12).